The goal of the proposed research program is to gain basic knowledge concerning the behavioral, metabolic, and neuroanatomical bases of food-intake control and body-weight regulation. The working model is that the medial hypothalamus contains a mechanism which mediates both excitatory and inhibitory control of feeding in response to body nutrient depletion and repletion, respectively: and it is hypothesized that this function may be the direct consequence of local metabolism of nutrients within the medial hypothalamus. The proposed work shall deal with four major issues: 1) What is the precise behavioral pattern of energy intake regulation? Feeding patterns of rats will be monitored after intragastric, intravascular, and intracerebral administration of glucose and amino acids. 2) Where in the brain is the regulatory process initiated? Discrete lesions to the substructures of the medial hypothalamus-- arcuate n., ventromedial n., dorsomedial n., and dorsal longitudinal fasiculus--will be inflicted. A battery of motivational and emotional tests will be employed to attempt fractionation of sybsyndromes which follow more extensive medial hypothalamic damage. 3) What metabolic information channels are critical for the regulation? A series of studies will test whether greater retention of nutrients in the medial hypothalamus as apposed to the rest of the brain is a mechanism by which long-term feeding behavior is stabilized. 4) Finally, the proposed hypothalamic model for regulation of feeding behavior shall be experimentally contrasted with predictions derived from other recent theories concerning hypothalamic participation in the regulation of energy intake and body weight.